Turning your unicycle into a generator?

I was considering trying to figure out how to rig my 36’er to provide power while I ride using a similar set-up to a faraday’s disk or a variable speed dynamo similar to those found in wind turbines(scaled down of course). Has anyone here tried this before or have any tips? I think my only problem would be going from DC to AC.

Wow, sounds very complicated and a great idea… i have never heard of this but sound amazing if you can do this device. Good Luck (btw sorry i couldn’t help at all):stuck_out_tongue:

You could just buy one of the bottle-type generators to mount on it.

Bear in mind that they have to go at reasonable speed to generate, and then don’t give off a whole lot of light.

Those bottle-type generators are hugely inefficient. Not only do they not produce much power, but they sap a lot of energy from the rider with the extra resistance they put on the tyre.

A more modern approach is something like this;

It’s driven by a magnet on the spokes that passes a coil mounted on the frame to induce current. The power isn’t that great from these either, but at least the resistance is negligible (the web site claims there is no resistance, but if that’s the case, it’s the scientific breakthrough of the century!). I guess you could add more magnets or more coils to increase the output.

Ductape, why do you want to go from DC to AC? A dynamo naturally produces AC current, but this is easily converted to DC with a couple of diodes.


Busch and Muller Dymotec bottle dynamos are supposed to be way more efficient than the old dynamos. They run off the tyre sidewall, so should work on a coker. They are quite expensive though.


I’ve got a dynamo hub on my bike - it is very efficient, and provides loads of energy for running lights (enough front light for riding in complete darkness plus a really bright back light), without noticeable extra effort, but that isn’t an option on a coker.

With the LED lights that are available nowadays, you can power a really bright front light off a dynamo.


You just want to charge your ipod, right? Not run lights?

yeah just want to be able to charge my ipod or cell phone while I ride.

Why AC? What voltage, current? What purpose?

I’d be a bit wary of charging a phone / ipod off a dynamo - we have a dynamo phone charger at work, that fits on a bike, but the phone it has been used on, the battery does funny things and doesn’t work as well as the other phones, it didn’t seem to like being charged with the dynamo. Ours was a cheap no-brand - according to http://www.treehugger.com/files/2007/01/motorolas_bike.php motorola are making a bike charger - which is more likely to be well protected.

Going from AC to DC is quite simple, but you do need some vaguely clever circuitry to smooth things out / limit voltage if you are attaching delicate electronics to it. One thing to do would be to charge a cheap AA battery pack with the dynamo, then use that to charge the expensive toys with the non-replaceable batteries etc.

It’s probably not worth building your own dynamo - given how long it took shimano to build a dynamo hub that is vaguely efficient (about 10 years), it probably is quite a hard task to build something more efficient than the best bike dynamos that attach to the tyre.


You might want to consider one of those solar backpacks.

Or simply a FreeLoader.
Very small, charges most phones/ipods/game boys/PSP/nintendo plus anything that can be charged via USB.
I’ll be reviewing one in the next issue of Uni.

They look like they’re great. However, I bought one last spring, and after about 8 hours in reasonably* sunny conditions, it was able to boost my phone charge from around 35% to 45%. So I took it strait back to the shop. Not sure if I had a faulty one or if they just don’t live up to the hype… but I look forward to reading the review.


  • reasonable for the UK at that time of year

You might need to gear it up if your using it with a big wheel.